/Engine/Plugins/Experimental/LandscapePatch/Source/LandscapePatch/Public/LandscapeTexturePatch.h
Determines where the patch gets its information, which affects its memory usage in editor (not in runtime, since patches are baked directly into landscape and removed for runtime).
enum ELandscapeTexturePatchSourceMode { None, InternalTexture, TextureBackedRenderTarget, TextureAsset, }